Previous studies of spatial development within the context of the Center have been limited and focused on spatial analytic processing in a subset of population groups. In this phase of the Center we will expand our study of spatial processing to systematically examine the relations between the various levels of spatial processing. Performance on spatial cognitive tasks may require different levels of spatial processing. Therefore, we need to define and study spatial processes ranging from the most basic attentional mechanisms to aspects of complex planning, and to compare profiles of deficit and normal processing across these levels of processing. The focal lesion populations will be used as the basis for generating specific hypotheses about possible associations and dissociations in spatial processing as they are related to lesions in particular brain regions. The focal lesion population constitutes a core population within the Center in that they are the group for whom we have the best descriptions of neurological deficit, and the group for whom we can make the strongest predictions about performance profiles within the area of spatial processing. The provide a means of defining how spatial processes can come apart. In this sense, the focal lesion population provides a window on normal development. If profiles of impairment reflect normal points of cleavage in the spatial analytic system, then based on our findings,, it should be possible to design studies which in the performance of normally developing children is made to echo the profiles of children with early injury. The study of the focal lesion population provides the opportunity to create cycles of confirmatory testing which can help to define the nature or normal processing and as well as to specify patterns of impairment. All of this work can be extended to the study of population with less well defined lesions. Four subdomains of spatial processing will be examined: will be initiated through a new collaboration with Eric Courchesne at UCSD. Dr Courchesne has an international reputation for studies of attention in normal and impaired populations. He has proposed a series of studies focused on basic mechanisms of attention. These studies are important to our understanding of performance in other spatial domains. Our studies of spatial cognition will include both an extension of our work in spatial analysis as well as a new study of mental rotation. Tasks of spatial memory will include a new memory for location task and the memory task using the Rey Osterreith Complex Figure. Finally, will begin to examine the development of executive functioning.